Prop



Jan. 18, 1955 s. A. J. LILJENDAHL 2,699,914

' PROP Filed Oct. 11, 195o INVENTOR SVEN ALGOT JOEL LILJENDAHL WW ATTORNEYS United States Patent The present invention relates to a prop having at least one lengthening piece which is slideable in a longitudinal slit between two uprights constituting the main part of the prop and being, by means of a squeezing device, compressible around the lengthening piece so that this is held in position. The invention has for its object to provide such a device having a secure engagement between the lengthening piece and the uprights and which admits of an easy variation of the length of the prop within wide limits. The invention consists substantially therein that the lengthening piece, at least on its side thereof facing the one upright, is provided with a concave bearing surface opposite the squeezing device. Preferably the lengthening pigce is made with a concave bearing surface on its both si es.

The invention will be more closely described with reference to the accompanying drawing on which Fig. 1 shows a prop according to the invention, arranged in supporting position. Fig. 2 shows a lower lengthening piece in the prop in perspective view whereas Fig. 3 illustrates an upper lengthening-piece, also viewed in perspective. Figs. 4 and 5 illustrate a squeezing yoke as viewed in lateral projection, partially in section, and from above respectively. Fig. 6 is a fragmentary view of a detail included in Fig. 1, as viewed in perspective.

The prop is constituted by two prismatic uprights 1a, 1b preferably of rectangular cross section which are held together at suitable places by means of wooden pieces 2 so that the uprights will be parallel with one another. In unactuated or free condition the uprights 1a and 1b, preferably being planks, are quite straight while it is assumed that they have an elasticity normal for wood. They form between themselves slit-shaped interspaces having normally parallel lateral walls.

The upper lengthening-piece 3a is shown in Fig. 3 whereas the lower lengthening-piece 3b is shown in Fig. 2. The lengthening-pieces 3a and 3b are made with parallel flat sides along the major portion of their length. The lengthening-piece 3a is, however, close to its lower end, provided with shallow concavities 4a and 4b on its opposing flat sides as indicated on the drawing. The lengthening-piece 3b is provided with both upper concavities 5a and 5b and lower concavities 6a and 6b each similar to those in the piece 3a. To provide a suflicient guidance in mounted position the lengthening-piece 3a is provided with two flanges 7a and 7b, for instance, in the shape of two transverse wooden pieces which cooperate with the longitudinal narrow sides of the uprights 1a and 1b. At its top the lengthening-piece 3a is provided with engagement means 8a, 8b protruding upwards and intended to form a holder, for instance, for a joist 9 adapted in known manner to carry a temporary floor 10 for casting a concrete flooring, a concrete vault or the like. The lengthening-piece 3a is furthermore provided with an offset, a projection or the like, for instance, in the form of a stud 11a, as shown, and a corresponding stud, provided on the opposite side but not shown on the drawing. The lengthening-piece 3b is provided with flanges 8c, 8d, for instance, in the form of boards secured on the narrow sides of the lengthening-piece and projecting therefrom to engage the narrow sides of the uprights 1a and 1b. At least adjacent the concavities 5a, 5b and 6a, 6b respectively said flanges are adapted to engage, on the one outside of the lengthening-piece, only the one upright, such as 1b, and on the opposite side of the lengthening-piece only the other upright, such as In. This has for its object to prevent that, in case of a swelling of the wood, such as due to humidity, the lengthening-piece will stick to the upright.

An upper squeezing yoke 12a and a lower squeezing yoke 12b are adapted to squeeze the uprights 1a and 1b elastically together so that the insides of the uprights will bear against the concavities 4a, 4b and 5a, 5b respectively. The design of the squeezing yokes is seen in Figs. 4 and 5. A U-shaped iron consisting of a back 13 and two legs 14a, 14b forms the squeezing yoke proper. Flange-shaped reinforcements 15 are secured and preferably welded onto theoutsides of the back 13 and ofv the legs 14a, 14b so as to make the yoke very rigid. The inside of the back 16 is preferably provided with frictional means, such as points, edges, scores or the like 16. If points or edges are provided they should project inwards only comparatively shortly and are not intended to cut the wooden fibres if forced onto the uprights. If scores are provided they should not be too wide and deep for the same reason. Disregarding the frictional means and considering the inside of the back 13 as a whole this provides a substantially flat engagement surface admitting a very high pressure to be applied to'the outside of the uprights without crushing the wood fibres. At the extremities of the legs an eccentric device is rotatably journalled. This device consists of two eccentric rollers 17a, 17b rigidly united and preferably integral with an intermediate bolt 18 being cornered, such as square or hexagonal. The rollers 17a and 17b are provided with bearing pins 19a and 19b projecting into slots 20 in the legs 14a and 14b.

The slots 20 are so shaped that two rotary positions for the pins 19a, 19b are formed, i. e. a lower position corresponding to that shown in Figs. 4 and 5 as drawn in full lines and an upper position at 21 in which the rotary axis of the device is spaced from the back 13 at a greater distance than in the lower rotary position indicated on the drawings. Between the eccentric rollers 17a and 17b there is inserted a rigid plate 22 adapted to take up the pressure from the eccentric and transfer it to the prop. As seen in Fig. 4 this plate is somewhat vaulted so that its outside is concave as viewed in a vertical cross section whereas in a horizontal section the outside of the plate is straight so as to provide an elongated bearing contact with the outside of the adjacent upright 1aor 1b respectively thus admitting of a high pressure being applied on the plate without crushing the wood fibres.

The inside of the plate is preferably provided with points, edges, scores or other frictional means of substantially the same nature as those described with'refer ence to the back 13. The plate is provided with two abutments 22a, 22b at one side engaging the top and bottom sides of the leg 14b and abutments on the other side, one of which is shown at 22c in Fig. 5, which engage the top and bottom sides of the leg 14a. Said abutments admit the plate to move along the legs 14a,v

14b. The yokes 12a, 12b are adapted to be thrust onto. the prop as shown in Fig. 1 adjacent the corresponding concavities of the lengtheningapieces'. rollers 17a, 17b may then be rotated, for instance, by means of a stout wrench or the like engaging the corner portion 18. The plate 22 is then forced inwards to-. wards the upright 1a whereas the back 13 is brought tov bear againstthe upright 1b. Upon increasing the pressure the uprights 1a and 1b are bent elastically inwards so as to bear against the surfaces of the corresponding The free ends of the legs 14a, 14b of the.

concavities. yoke are held on an unvariable level in relation to the uprights 1a, 1b through their engagement with the abutments 22a to 22d of the plate 22. If upon a displacement of the lengthening-pieces in relation to the uprights the yokes are appreciably displaced in relation to the concavities, this would mean a great inconvenience. To prevent this the lengthening-pieces may be provided with catching devices consisting, for instance, of stud 1112, provided on one side of the lengthening-piece 3a and a similar stud on the other side of the piece and which project out into the path of the yoke 12a so that the stud, upon short sliding down of the lengtheningpiece, will bear against the yoke.

In the lengthening-piece 3b the catching device is constituted by, for instance, two blade springs, one of which P tented Jan. 13, 1955v The eccentric is shown at 11c whereas the other one, on the opposite side," is"not"shown"1rr"the' drawing; Inthis Way it" is assured that upon very heavy increases in the load caused, for instance, by the swelling of the material,

theretwill occur-a -short yield under a rapidlyincreasing resistance counter-acting the-yield? To facilitate- -an adjustment of: the displacedtpositron of -the I lengthening-piece 3b in= relation to the uprights Id and-1b a lever 23 may* beused which. is providedwith astud 24-intended toengage anaperture'25 in thelengthening 'piece Sb'and aswingablelink- 26 provided with 'a-studi27 adapted-'to-engageany one of a number of ali'gned holes-28 in the upright 1a.

If the pressure of the eccentric rollers1721, 17b is reduced by rotating said wrench upwards it is possible,

by applyingamoderate downward force on the outer end of the-lever '23, to-bring about that -the-uprights 1a and 1b gradually" s'tart-to slide downwards in relation to the lengthening-piece -3l "under a full control of the operator. If the ramp is to beraised a similar procedure is followed although the lever 23 is instead swung upwards; Asso'on as the des-ired'position has been reached the-eccentricrollers' 17a-' and 17b are again tightened by turningthe'wrench. downwards; The gearing ratio of the'lever'23 may easily be made sohigh that a shifting force of sufficient strength is obtained for all practical requirements.

Aboveit has been assumed that the uprights and the lengthening-piece havebeen made of i wood. Nothing however,- prevents them from being made, instead, of iron or other metal.

From the design of the prop and the lengtheningpiece it isunderstood that the prop may take up both compressional and tensile strain in its longitudinal direction;

By providing concave bearing surfaces at both ends- 1. A- prop comprising two spaced uprights, said up-- rightsv being normally prismatic and runn ng in parallel, a lengthening piece normally slideable 1n the long tudinal spaceformed between the uprights at each end' thereof, at least one concave recess being formed in at least one of thesidesof the lengtheningpieces facing the uprights, said-sides being otherwise-parallel with one another, and a squeezing device acting'on the outsid'es of bothuprights adjacent said recess and movable along the uprights was to continuously register with said recess tosqueezesaid uprights together against the said sides ofthelengthening pieces with such a force that the corresponding upright isbent-into frictional engagement.

with the walls. of said recess, and lever means pivotally mounted on oneend thereof to one of said lengthening piccesa-ndadapted to engage one of said uprights to position said lengthening piece:

2.'A prop as claimed in claim 1, in which each of' the said lengthening pieces is provided with concave recesses-on both sides thereof, said recesses being in the same transverse plane.

3. A prop as claimed in claim 1 in which the sa1d squeezingdevicecomprises a yoke-surround1ng both of thesaiduprights, and each. of the said lengthemng pleces is provided with abutment means adapted for engagement with the said yoke so that shding movement of the lengtheningpie'ceinto" theuprights will bring about movement of the said yoke? with the lengthening piece thereby to maintain the yoke in alignment with the recess in the side of the said lengthening piece.

4. A prop as claimed in claim 3 in which the said abutment means comprises spring means.

5. A prop as claimed in. claim 1 wherein the said squeezing device comprises a yoke extending around three sides of theuprights', an eccentric carried the yoke on the fourth side of said uprights guided in said yoke for movement toward. anclaway from theladjacent uprights, and a plate in the yoke between the eccentric and the adjacent side of the uprights adapted for transmitting thrust to. the sideof the upright upon actuation of the said eccentric in the yoke.

6. A prop as claimed in claim 5 in which the said plate. is provided with abutment means engaging. the top andbottornedges of the yok'efor guiding it toward and away from the adjacent upright and serving to prevent movement of the plate relative to theyoke in longitu: din'al direction of the said uprights.

7. A propaccording to claim 5 in. which the. said eccentric 1s 'adjustaoly mounted in the said yoke so. that.

8.- In a prop; a pair of uprights connected together. ln'spaced parallel. relation to define a space therebetween.

in" the direction'of'the length of the uprights, the inside faces of. said uprights being fiat and parallel, a lengthening'piece slideable in the space between the uprights at each end thereof in engagement with the said flat faces, concave recess means in at least one of'the sides of said. lengthening pieces adjacent one of the said flat faces, a three-sided U shaped'member around said-uprights in a plane transverse to the length thereof and With the open'sideof the member opening at the side of one of said uprights opposite the said flat face thereof; an eccentricshaft extending between the legs of said member at the said open side thereof, an eccentric on said shaft, and a plate-interposed between the eccentric and the adjacent side of the upright whereby actuation of said eccentric will apply squeezing pressure to said up rights, said member being positioned in the region of said'concave recess whereby the uprights will be squeezed in a. manner to. press the upright adjacent the recess therein thus to bind the said upright and lengthening pieces together, and lever means pivotally mounted on one end thereof on one of said lengthening pieces and adapted to engage one of said uprights to position said lengthening piece.

9. A prop as claimed in claim 1 with link means having one end thereon pivotally' mounted on said lever means,.and the other end of said'link means having lug means thereon" for engagement with an aperture on one of said uprights.

References Cited in the file of this patent UNITED STATES PATENTS 656,053 Shaffer Aug. 14, 1900 1,084,236 Siderits et al7 Jan. 15, 1914 1,776,439 Kinninger Sept. 23, 1930 2,217,188 Snyder Oct. 8, 1940 2,332,240 Lavalley Oct. 19, 1943 FOREIGN PATENTS 28,784 Great Britain Ian. 30, 1913 400,821 Germany Aug. 20, 1924 

